This invention relates to a connection fitting for connecting a pressure expansion vessel to a conduit system, in which a water flow flows, a diaphragm dividing said vessel into a cavity filled with water and a pressurized gas chamber filled with pressurized gas, wherein said connection fitting comprises a suction device, in which a suction is generated by said water flow, and a water exchange flow is generated by means of said suction along a flow path extending parallel to said water flow and through said cavity.
This invention particularly relates to a connection fitting of this type, wherein a plug valve having a valve plug is arranged to shut off said parallel flow path, said connection fitting comprises a fitting basic body having a connecting socket for said pressure expansion vessel, said valve plug of said plug valve is arranged in said connecting socket for said pressure expansion vessel between a first formed body forming said suction device and located adjacent to said water flow and a second formed body likewise located in said connecting socket on the side of said pressure expansion vessel, and said second formed body has a tubular central portion and an annular portion surrounding said tubular central portion and connected to said tubular central portion by webs.